Speaker matching and selecting device



0a. 17, 1939. P. J. FABER 2,176,732

SPEAKER MATCHING AND SELECTING DEVICE ffy/MMA@ Oct; 17, 1939. P. J. FABER 2,176,732

SPEAKER MATCHING AND SELECTING DEVICE Filed Jan. 15. 1938 3 Sheets-Sheet 2 Z000 -fL @ier fj/Haber,

Oct. 17, 1939. P. J. FABER 2,175,732

SPEAKER MATCHING ND SELECTING DEVICE Filed Jan. 15, 1938 3 Sheets-Sheet l soon/n o c O C o c O C C o soo o soo o soo o soo o 50o o looo o looo o nooo o looo 0 looo o |500 o soo o lsoo o soo o lsoo o zooo o zooo o zooo o zooo o zooo o zsoo o zsoo o zsoo zsoo fn zsoo INVENTOR.

Mj: Mii/ YPatented Oct. 17, 1939 UNITED STATES PATENT ori-ics VICE Peter J. Faber, Chicago, Ill., assignor to Moni;- gomery Ward & Co., Incorporated, Chicago, Ill., a corporationy of Illinois Application January 15, 1938, Serial No. 185,245

17 Claims.

My invention relates to a device for matching speakers to amplifiers, and selecting certain speakers in public address systems andthe like.

In the public address systems now in common use, it isfrequently necesary to change thenumber of speakers connected tothe amplifier. Since the usual practice isto use impedance adjusting transformers to regulate the impedance ratio, it

becomes necessary to change the transformer connections each time a change is made in the number of speakers used in the system. An ordinary unskilled person has diiculty in determining the connections of the transformer to be used. It is generally true that for the maximum 1| undistorted power output for any given tube (or tubes), the load impedance should be approximately twice that of the tube. Since the primary of the impedance adjusting transformer forms the load for the tube, and since the secondary of the impedance adjusting transformer must have the proper number of turns for correct power transfer from the primary to the secondary and thus to the speaker, so that the impedance of the speaker and the secondary are equal, it can be readily understood that a change in the number of speakers will destroy the balance of the system, necessitating a change in the transformer turns ratio.

It is an object of this invention to provide a so device whereby additional speakers may be added bymerely changing the set of an indicator pointer to a public address system already in operation and still secure proper undistorted power transfer without disturbing the wire connections 35 to the transformer.

It is a further object of this invention to provide, in the same device, an arrangement whereby selected speakers may be used as theiirst series of speakers on the circuit, and additional speakers 40 may be connected to the system from predetermined locations, as they may be needed. This is made necessary by the fact that an address system adjusted for a small crowd might have the speakers located in an advantageous point fairly close to the source of entertainment such as an orchestra or` the like. As the crowd becomes larger, additional speakers farther back and in certain locations might be desirable. By merely readjusting the indicator, the speaker desired may be brought into the system in order.

Another object of this invention is the provision of an' inexpensive-device using a single transformer for the varied number of speakers.

This eliminates the expensive additional equipment now necessary to be'carried wherever additional speakers are apt to be needed.

It is a further object of this invention to provide an indicator means that is easily understandable and can be quickly adjusted. 5

It is an object to provide a distribution box and structural connector unit having a plurality of sockets or connections and a switch control connection connecting in speakers.

It is an object to provide a plurality of tap conl0 nectors combined with matching transformers and switch controls in a Speaker matching and distribution box for public address and other speakers.

It is a further object to provide a speaker disl5 tribution box having the speaker matching and selecting qualities of this invention which box may be located at some point as near the speakers as possible and does not have to be located in or near the amplifier.

It is another object to provide an arrangement whereby additional distributor boxes accommodating additional speakers may be used when desired by merely changing one Contact on the distributor box when the additional .boxes are added to the circuit.

Other objects and advantages of this invention will appear as the nature of the improvements is better understood, the invention consisting substantially in the novel construction and the combinaton and arrangement of parts hereinafter fully described, illustrated in the accompanying drawingsand finally pointed out in the appended claims.

The form of the invention herein shown and described presents a preferred embodiment thereof, and delineates its adaption to practical use.

It is to be understood that the present disclosure is to be considered from the illustrative stand- 'point and not as imposing restrictions or limita- 40 tions on the invention.

In the drawings:

Figure 1 is a perspective view of the external arrangement of the box embodying the present invention, showing the top, front and one end of the box.

Figure 2 is a plan view taken on the line, 2--2 of Figure 1,1ooking in the direction of the arrows.

Figure -3 is a circuitv diagram showing the speaker matching and selecting circuitV used in this invention.

Figure 4 is a modification of the diagram of Figure 3, the speaker selecting contact being omitted.

Figure 5 is a circuit diagram showing a plu- 55 the speakers are inserted.

wise, a different ratio of .vices connected in parallel on a 500 ohm line from the ampliiier.

Figure 6 is a modification ofthe diagram of Figure 3 showing the transformer primary with leads or taps to the amplifier.

Referring more in detail to the construction shown in the various iigures, number I0 is the box or container for the mechanism constituting this invention. This box has the front II, the ends I2 and I3, the rear I4 and the top I5.

The front panel I carries a dial or indicator I6, which is shown as marked for calibrations. The switch knob I1 is located so that the turning of the knob will bring one end into line with a calibration on the dial. In this connection the knob I1 is preferably narrowed at one end to form a pointer, as shown at |8.

'I'his pointer is a quick guide for the eye in searching for the calibration to which the knob is turned. v

Each end of the box I0 carriesthe socket contact into which the connector cords or wires of These sockets are numbered I9, 20, 2|, 22, 23 and 24 respectively, as shown in the drawings,

I have shown at one end the terminal contacts 25, 26, 21, 28, 29 and 30 for the primary side of the transformer 3|. To protect these contacts and to protect the operator from shocks, I have provided the cover plate 32,'which is held in place by small bolts and nuts 33. The transformer 3| is preferably the universal type of transformer in general use, and a very good transformer has a primary with. taps of 500 ohms, 1000 ohms, 1500 ohms, 2000 ohms, and 2500 ohms, and a secondary with taps of 500 ohms, 8 ohms, 4 ohms, 2% ohms, etc. `It has the core 34, windings 35, and is suspended from the top I5 by means of bolts and nuts 36. by the switch knob |1.- accurate contact, the switch is provided with the guide disk 38 which is notched at intervals around its periphery. The spring 33 contacts and main tains a tension on the notches, thus keeping the switch in proper alignment. These notches are preferably located so that pressure of the spring 39 will bring the pointer I8 into alignment with the calibrations on the dial I6.

The various leads 40, 4|, 4.2, 43, 44 and 45 from the secondary taps of the transformer are arranged for proper contact bythe switch 31. 'I'he connector 46 runs from the switch to one of the contacts of each socket I9, 20, 2|, 22, 23 and 24; The other contact on each socket is the common or ground contact 41 from the secondary of the transformer 3|. The sockets as shown have two extra holes, which are not essential however, but are here provided as guide holes and the like. Referring in particular to the circuit diagrams, Figure 3 shows a circuit in which the speaker contacts are wired so as to be brought into use by turning switch 31 to the indicated number. As the pointer is turned clockturns on the secondary in contacted andthe sockets I9, 20, 2|, 22, 23 and 24 are contacted in'sequence and the contact is maintained for the first sockets contacted as the subsequently contacted sockets are brought into circuit. The scheme shown in this diagram of Figure 3 makes it possible to plug in six speakers (more if thev circuit is designed for more) and leave them plugged in whether it is desired `to use one or all or any number of them. The speakers should be arranged so that the rst 'I'he switch 31, is operated' To assure proper and rality of the speaker matching and selecting deone to come in, that of socket number. I3, will bev one that is to be used at all times when the circuit is operating. Those speakers or sockets on numbers 20, 2|, 22, 23 and 24 should be those desired to be used in sequence so that they may be cut out of the circuit or cut into the circuit as desired, this result being accomplished by merely adjusting the pointer'IB of the switch 31 at the indicated number. f

yIn Figure 4 the sockets I9, 20, 2|, 22, 23 and 24 are connected in parallel. It is not intended to'leave the speakers plugged into these sockets when speakers are not in use. It is immaterial which plug any particular speaker is plugged into in the arrangement shown in Figure 4, and

Vthe selector arrangement shown in Figure 3 is not present. As the individual speaker is plugged in however the pointer on the switch 31 is placed to the indicator showing the number of speakers in the circuit as shown in the diagram.

As will be evident from examination of lFigures 3 and 6, the circuit shown there is adaptable for incorporation directly into an amplifier; that is, it may be adapted to take the plate current directly from the tube of the amplifier for the primary, in which instance the primary taps will be changed to handle the impedance of the tube plates. The ratiofof turns of the secondary to the primary would be changed so that the secondary taps would have the proper impedance for the speakers.

In addition, the additional portion 48 of a circuit is provided so that the 500 ohms impedance on the transformer secondary is automatically cut out of the speaker circuit for the sockets, I8, 20, 2|, 22, 23 and 24, and is directed through circuit portion 48 to the 500 ohms output terminals, where it is available for use to operate distributor box located at a distance from the amplifier or a speaker with a l500 ohms impedance or any other electric device input; The terminal contacts 25, 26, 21, 28, 29 and 30 are provided so that additional distributor boxes may be connected to the circuit from the amplifier tube. 'I'he terminal contact 25 is conrequiring a 500 ohms contacts are for variation in the number of distributor boxes. -In the example shown, if you have only the one distributor box, the contact 28 which is the 500 ohm contact would be used in lconnection with the common contact 25. It two speaker boxes were in the line, the contact 21 which is the 1000 ohm contact would be used with the common contact 25 on each. 'I'his would give a primary impedance of 500 ohms to each of the two distributor boxes. As a third distributor box is added to the line then each of the distributor boxes in the line would have connections to the 1500 ohm impedance contact which is here shown `as number", or ii' more than three distributor boxes are in the circuit then the 2000 or 2500 ohm contacts number 29 or 30 respectively would be used with the common. Of course, the distributor box could be wired for additional contacts but it is not considered necessary to disclose any more in this application. It will be understood, however, lthat where two boxes are on the line, each box having/,the same range of impedance, the primary terminal contact used with the common primary terminal contact 25 would be set the same on each box.

Since the low impedance used by the ordinary speaker today-for example; eight ohmsmakes it dimcult to have the speaker more than thirty-five or forty feet from the amplifier tube .because of wire resistance and loss ofV power, it

address system in schools, factories and other places, where numerous rooms at long distances from the amplier are in the system.

Theform of invention herein vshown and described is believed to be a preferred embodiment thereof, but it is to be understood that the same is susceptible to change, variation and modification in the arrangements of the parts. 'I'he form illustrated, therefore, is to be taken from the illustrative standpoint only, and not as imposing restrictions or limitations upon the invention.

I claim:

l. In combination a container, a universal transformer therein, input connections to the primary of said transformer, taps on the secondary of the transformer with leads to an adjustable switch means, a switch knob located outside the container with connections to the switch means whereby movement of the switch knob changes the transformer secondary contact of the switch, an indicator on said container cooperating with the switch knob to indicate the position of the switch, a plurality of speaker contact sockets or the like carried'by the wall or walls of the container, a common tap connector from the secondary of the transformer to one contact on -each of thespeaker contact sockets and a lead from the switch to another contact on each of the speaker contact sockets, all ofl said mechanism operating to produce a load of desired impedance on the plate circuit of an amplifier or the like and to give impedance output of predetermined amount, the output being variable by adjustment of switch, whereby a variable number of speakers are operated.

2. In a device of the class described, the combination -of a container box, universal transformer therein with secondary taps at positions giving predetermined output, contact means for an amplifier or the like to the primary of said universal transformer, adjustable contact means to a plurality of speakers from the secondary of said universal transformer, said contacting means contacting the proper secondary tap,

watching the load impedance of the speakers whereby oneor more speakers are operated from said speaker contact means, and indicator means, in connection with said adjustable speaker contact means showing the number of speakers operable at a given time on said contact means.

3. As a unitary device, a transformer having selectable input and output connections, contacts to said input connections from a plate circuit or the like, contacts from the output connections of the transformer to an adjustable switch, contact rmeans from said adjustable switch to connections for speakers andthe like, and a common connection from the secondary of the transformer to said connections for speakers and the like.

4. In a device of the class described` the combination of a container, a transformer with primary taps for load impedance values in arithmetic progression, a secondary tap with outputs substantially equal to the input of the lowest primary tap, and having, also, a plurality of secondary output taps, each tap vof output to match respectively the load impedance value, and switch means matching the speaker contacts and the respective secondary tap for proper output to the speakers contacts in operation.

5. In a device of the class described the combination in a unitary arrangement of a universal transformer having adjustable primary taps for load impedance values in arithmetic progression,

a secondary tap with output substantially equal v to the input-of the lowest primary tap above the common, other secondary taps with graduated output to respectively match the load impedance value of a successive number of speaker contacts, cach speaker contact having substantially equal load impedance value, an output contact with load impedance substantially equal to the rst mentioned secondary tap, and a switch means manually operable to close the cirsecondary tap having proper impedance, and

contact means from said switch means accommodating a variable number of speakers. l

7. In a device of the class described, the combination of a transformer having input connections and adjustable output connections, of a manually operated switch means variable to contact any one of said output connections of -the transformer, corresponding contact means on the switch means contacting in sequence one or more speaker contacts.

8. In a device of the class described, the comf secondary taps for output accommodating one or more speaker contacts of equal load impedance, and manually operable switch means selecting secondary tap and corresponding speaker contacts, substantially as described.

9. A speaker matching and selecting device having a transformer with input contacts, each of said contacts being of different input capacity, said transformer having a tapped secondary with leads toa manually operable switch means, a plurality of connections from said manually operable switch means to a plurality of speakers, and a common connection from secondary of the transformer to said speakers.

10. A speaker matching device having a transformer with a plurality of input taps on its primary, each of said taps being for a different input capacity, a secondary on said transformer having output taps vcontactable by a variable switch means, separate contacts to a plurality of speakers from said switch means, whereby movement of said switch automatically cuts into or out of circuit as the case may be, the proper number of speakers contacts matching the load of the proper output tap of the transformer secondary, al1 o-f the speakers operable byI said device having a common connection to the secondary of the transformer.

11. In a device of the class described a combination of the universal transformer with secondary taps in positions giving predetermined output, contact means for an ampliier or the like to the primary of said universal transformer, adjustable contact means to a plurality of speakersl from the secondaryv of said universal transformer, whereby adjustment of the adjustable speaker contact means contacts the proper secondary tap matching the load impedance of the speakers. r

12. In a device of the class described a combination of the universal transformer with secondary taps in positions giving predetermined output, contact means for an amplifier or the like to the primary of said universal transformer,

adjustable contact means to a plurality of.'

speakers from the secondary of said universal transformer, whereby adjustment of the adjustable speaker contact means contacts the proper secondary tap matching the load impedance of the speakers, and indicator means showing the number of speaker contact means at any given time in the circuit.

13. In a `device of the class described the combination of a universal transformer with secondary taps at positions giving predetermined output, contact means for an amplifier or other sources of current, switch means adapted to contact in sequences the taps of the transformer ,secondary giving increased amounts of output, said switch means being likewise adapted for contacting and maintaining contact with a plurality of speakers contacts, whereby certain preselected speakers are brought into the circuit successively by operation of the switch means, While 4maintaining contact with the speakers previously brought into the circuit, said switch means automatically contacting the proper tap of the secondary to match the load of the speakers then in circuit, and a given connection from the secondary to the speakers.

1,4. In a device of the class described the combination of a universal transformer with secondary Ytaps at positions giving predetermined output, contact means for an amplifier or other sources of current, switch means adapted to con-A tact in sequence the taps of the transformer secondary giving increased amounts of output said switch means being likewise adapted for contacting and maintaining contact with a plurality of speakers contacts, whereby certain preselected speakers are brought into the circuit successively by operation of the switch means, while maintaining contact withv the speakers previously brought into the circuit, said switch means automatically contacting the proper tap oi the secondary to match the load of the speakers then in circuit and a given connection from the secondary to the speakers, and indieating means indicating the speakers in circuit at any particular time.

15. A speaker matching and selecting device, having a transformer with a plurality of input contacts, of respective values giving an impedance increase of substantially equal predetermined amounts; source of power; a plurality of said speaker matching and selecting devices connected to said source of power in parallel, the common contact of each of said speaker matching and selecting devices being connected to one lead from the power source, and an input contact on each of the devices having a value that when divided by the number of devices in the circuit substantially equals the impedance value from the source of power, being connected to the o her power lead.

,J 16. A speaker matching and selecting device having a transformer-of input contacts arranging from l0 to a number derived by multiplying the impedance of the power source by the number of speaker matching and selecting devices in the circuit, each of said contacts having a greater impedance increase than the last contact by an amount equal to the impedance oi -the power source, whereby-when the common contact of each speaker matching and selecting device is connected to one lead, the proper contact connected to the other lead on each of said speaker matching and selecting devices, is determined by multiplying the impedance of the power source by the number of speaker matching and selecting devices in the circuit.

17. A speaker matching and selecting device having a transformer of input contacts arranging from 0 to a number derived by multiplying the number 500 by the number oi' speaker matching and selecting devices in the circuit, each of said contacts having a greater impedance increase than the last contact by an amount equal to the impedance oi' the power. source, whereby when the common contact of each speaker matching and selecting device is connected to, one lead, the proper contact connected to the other lead is determined by multiplying the impedance of the power source by the number of speaker matching and selecting devices in the circuit, and the matching of each speaker matching and selecting device upon placing an additional speaker matching and selecting device into the circuit is accomplished by moving the last mentioned contact on each oi' the devices in PETER J. FABER.

CERTIFICATE OF CORRECTION. PatentNo. 2,176,752. i october 17, 1959.

- PETER J. FABER.v

It is hereby certified that error appears in ihe printed specification ofthe a'bove numbered patent requiring correction as follows: Page 2', first column, line 66, for the word in redis; page 5, first column, line 55, claim 2, for Qwtching". lread matching; and that the said Letters Patent should be read with this correction therein that the same my confo nnto the record of the.` case in the Patent Office..

lSigned and sealed this 50th da-y of April, A.l D. 19140.

Henry Van Arsdale (Seal) Acting .Commissioner of Patents.

CERTIFICATE OF CORRECTION. patentNo.f2,i76752. A october 17, 1959.

` .PETER J. FABER.y

It-y is hrebyoertified that error appars in 111e printed specifiation ofthe-above numbered :patent requiring corre'ction as follows: Page 2', first column, line 66, for' word "in" readis; page 5', first column, line 55, claim 2,4 for' {"wallzclhing lread. matching; and that the said Letters Patent should be read with .this correction there'inthat the same may conformuo the recordl of .tha case in the Patent Office.,

signed and sealed this 50th day o f April, A.. D. 19LL0.

Henry Arsdale (Se-Q.) Aoting dCommissioner' of Patents. 

